Electrical connector block for bus ducts



.1 Sept. 1951 M. E. BOWERS ELECTRICAL CONNECTOR BLOCK FOR BUS DUCTS Filed Oct. 29, 1947 Patented Sept. 25,1951

OFFICE ELECTRICAL CONNECTOR BLOCK FOR BUS DUCTS Marsden E. Bowers, Detroit, Mich.

Application October 29, 1947, Serial No. 782,755

2 Claims. I

The present invention relates to electrical connector blocks, particularly for installation in metal ductwork, junction boxes, and the like to facilitate the tapping on of branch conductors.

An important object of the invention is to provide improved connector block means adapted to be so installed and incorporating such inherent safeguards that branch conductors may be connected to live main power leads Without shutting off the power from the main power lines yet with relative safety to the workmen.

Another object is to provide such an improved connector block construction which permits the making of branch connections to main power lines in a quick, simple and safe manner, without severing the main lines and without shutting them down, as previously indicated, the arrangement being such that there is very little chance of accidental contact between any part of the workmans body and a live conductor, or the creation of a short-circuit, in event the workmans hand or a tool should slip or fall, or an unintended move should be made by the workman due to loss of balance or footing.

A related object is to provide such an improved connector block which is simple and inexpensive in construction, rugged, quick and easy to install, and which incorporates housing portions formed of insulating material and so shaped and arranged as to provide effective protection against accidental injury to the workman even though the tool used by him for the making of branch line connections should slip in such manner as to come into contact with other portions of the structure near the actual terminal part being worked upon, or even into simultaneous contact with a terminal and another part near the same.

Other objects and advantages will be apparent upon consideration of the present disclosure in its entirety. In the drawing:

Figure 1 is a side elevational view, partly broken away, of a portion of a sheet metal duct containing electrical conductors and equipped with connector blocks incorporating the principles of the present invention;

Fig. 2 is a bottom plan view of a portion of the same on a larger scale and with the cover removed, taken as indicated by the line and arrows 2-2 of Fig. 1;

Fig. 3 is a cross-sectional view upon a still larger scale, taken as indicated by the line 3--3 of Fig. 1, and looking in the direction of the arrows; and

Fig. 4 is a cross-sectional view taken substantially on the line 4-4 of Fig. 3 and looking in the direction of the arrows.

Referring now to the drawing, reference character I'O designates a troughlike sheet metal duct housing structure indicated as supported in inverted position and depending from a ceiling I2 upon suitable hangar brackets 14 attached to the ceiling by anchoring screws IS. The open face of the duct is closed by a hinged cover I6. Ductwork of this character is well known in the art, and is ordinarily furnished in standardized sections, each section being provided with a cover extending its full length and the entire interior of the duct being readily accessible when the cover is opened.

The side walls of the channel-shaped duct body and also the bottom wall (shown uppermost in the inverted installation depicted) are provided with knockout sections as IT, l8 which are also ordinarily located at standardized distances along the duct.

Each of my improved connector blocks comprises a generally boxlike body which is preferably formed of porcelain or other ceramic or equivalant material of relatively inexpensive character but high insulating value, and includes side walls 20, 22 so spaced from one another as to fit easily into the duct body or other receptacle which it is designed to fit, and end walls 24, 25 which are provided with V-shaped cutout notches as 26, 28. The spacing of the end walls may substantially correspond to that between the side walls, so that the walls define a box having an open face accessibly located directly beneath the hinged cover 16 when the block is installed in the duct. The bottom wall 21 of the boxlike block body is provided with a longitudinal rib 30 adapted to space the bottom of the box from the bottom of the duct, as best shown in Fig. 3. The rib is narrower than the box so that when the block is installed passageways 53, 51 are left between the block and duct on either side of the rib.

An aperture 32 extends perpendicularly through the bottom 2'! and rim 3! through which a bolt as 34 is adapted to be passed. In installing the block, the stem of the bolt 34 is passed through an opening as I9 formed by dislodging a section of one of the knockout portions as l8 in the bottom of the duct. The head of the bolt overlies the interior of the bottom Wall 21 of the box, while a conventional nut as 35 may be fastened to the exposed portion of the bolt outside the duct to secure the block in place. The head of the bolt 34 may be set in a recess 36 and covered by a relatively thin insulating panel 38.

A conductive plate 40 which may be formed of copper is fitted in the box and held against the panel 38 as by means of screws 42 which extend into suitably tapped openings in the plate, being projected through appropriately positioned counterbored apertures 44 which extend through the bottom wall 2'! of the box. The heads of the screws 42 may be recessed in the counterbored outer ends of the openings 44, as shown in Fig. 4, and two of the screws 42 may be provided, positioned at diagonally spaced points near opposite corners of the plate 40. The screws also extend through suitably positioned openings (undesignated) in the panel 38 and so secure the plate and panel in position. The arrangement described also serves to provide retaining means for the bolt 34, permitting the block assembly to be handled and installed as a unit, simply by projecting the end of the bolt through one of the knockout openings and attaching a nut, as previously indicated. A channel, as 45, is longitudinally formed in the surface of the plate 40 to form an enlarged and efficient conductive seat for a stripped conductor as 46 laid therein. A top clamping plate 48, also formed of conductive material and generally similar to the bottom plate 46 is adapted to be clamped against the opposite surface of the conductor as by means of clamping screws 52. The screws 50, 52 extend through relatively loose and unthreaded openings 54 in the top plate 48 and into tapped openings as 55 in the bottom plate 4!]. Screws 50, 52 also serve to retain connector terminals to which branch conductors are adapted to be connected. The terminals are formed by relatively flat pierced luglike portions 56 through which the stem of one of the bolts 50, 52 is adapted to be passed, the extremity of each of the portions 56 being provided with suitable wire fastening means, shown as comprising a binding post construction having a lateral opening as 58 into which a wire to be secured may be passed and a binding screw as 60 enabling clamping such a wire tightly with respect to the terminal. A branch conductor 83 is shown so secured in Fig. 4.

As best shown in Figs. 2 and 3, the clamping screws 5i], 52 are arranged upon opposite sides of the channels 45, 4! so as to extend upon either side of a main conductor laid therein. Each of the clamping screws may serve to secure two terminal assemblies, so that provision is made for the connection of four branch conductors to the main line within each block. It will also he observed that although all four of the terminal assemblies lie within the boxlike enclosure formed by the connector block, tappedon wires such as the branch conductor 83 may extend through one of the end openings as 28 for connection to one of the terminal posts.

For purposes of illustration three of my improved connector blocks are shown installed in a duct assembly carrying a three-phase supply system comprising the main feeders 46, 49, 5|, although it will be appreciated that my improved block construction is equally applicable to directcurrent systems or to other systems carrying either single-phase or polyphase supply. The individual connector blocks are successively connected to each of the main feeders, so that all parts within each boxlike connector block are at the same potential. With a three-phase supply system, connection may be made to any two or to all three of the main feeders by means of branch conductors which need not extend along the duct a distance greater than that represented 4 by the spacing of three successive connector blocks.

In the representative installation depicted in the drawing, the block shown at the right in Fig. 2 is generally designated A, and it will be noted that feeder 49 is stripped at the block A and connected to the terminal structure thereof in the manner previously described. Feeder 49, however, extends freely beneath the blocks B and C, being unconnected to either of these. Feeder 46, which extends freely under the block A is stripped at the block B and run through the center thereof for connection to its terminal structure in the manner described and as clearly shown in Figs. 2, 3 and 4. Conductors 49, 51 run freely beneath the block B, while conductor 5!, which also extends freely beneath the block A is stripped at and connected to the block C, through which the conductors 46, 49 run freely. This method of connection may be successively repeated, and similarly positioned blocks may be arranged within and along each section of the duct, or if preferred only certain duct sections may be provided with such connector block installations.

Where only a single-phase tap-on connection is desired, branch conductors as 62, 53 may be led to any two adjacent blocks as A, B, through one of the knockout openings in the side of the duct, while where a three-phase tap-on connec tion is desired, one branch conductor as BI is led beneath an intermediate block as B for connection to the block A while the other two branch conductors 82, 83 are connected to the adjacent blocks C and B to complete this three-phase connection, as also shown in Fig. 2.

In the preferred construction shown in the drawing the binding screws 60 are indicated as provided with sockets as 6| of the Allen-type, and electricians making tap-on connections need only be provided with a single Allen wrench of the proper size, equipped with an insulating handle. It will be seen that even while the system is carrying a dangerously heavy voltage, the binding screws may be loosened, and a branch conductor which has been preliminarily stripped at its end may be handled by the insulation, inserted in one of the terminal posts, and the binding screw tightened, without danger of exposing the workmans body to the current.

The channels 53, 51 formed by the ribs 30 beneath the blocks are also large enough to permit branch conductors to be easily pushed through the spaces upon either side of the rib, the conductors being handled by the insulation thereon, and safe connections may accordingly be made to a live system.

Since each connector box assembly has its terminal portions connected to only a single feed line, so that the metallic portions thereof are all at the same potential, and since such portions are shielded from the metallic (and ordinarily grounded) walls of the duct by the insulating walls of the connector block, it is literally impossible for the Allen wrench or other tool employed by the workman to complete a short circuiting connection between the live parts and any other feed line or the body of the duct.

While the preferred embodiment of the invention herein disclosed is well calculated to fulfill the objects and advantages first above stated, it will be apparent that the invention is susceptible to variation, modification, and change without departing from the proper scope-and fair meaning of the subjoined claims.

I claim:

1. A connector block comprising a hollow boxlike structure of substantially rectangular form formed of insulating material and open upon one side only, walls defining a part of said structure having aligned openings extending therethrough through which an uninterrupted conductor may extend, spacing and attaching means for securing said structure to a support in spaced relation with respect thereto, including a spacing element narrower than said structure whereby conductors may extend outside the boxlike structure upon either side of said spacing element, an attaching member extending from the interior of said structure through one wall thereof and through said spacing element, clamping and connecting elements within the enclosure defined by said structure and accessible through the open side thereof, insulating means between said attaching member and said clamping and connecting elements, and common holding means for preventing separation of said attaching member and said clamping and connecting elements from said boxlike structure.

2. Means as set forth in claim 1 in which said 6 attaching member comprises a bolt having a head lying within said structure and separated from said clamping and connecting means by said insulating means.

MARSDEN E. BOWERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,022,423 Jordan Apr. 9, 1912 1,148,699 McWilliams Aug. 3, 1915 1,244,099 Kneisel Oct. 23, 1917 1,266,440 Finkelstein May 14, 1918 1,995,855 Lee Mar. 26, 1935 2,107,915 Tashjian Feb. 8, 1938 2,111,939 Rowe Mar. 22, 1938 2,281,515 Ruggieri Apr. 28, 1942 FOREIGN PATENTS Number Country Date 144,604 Austria Sept. 15, 1935 475,946 England Nov. 29, 1937 

